Test on mirror support prototypes

M. Lenti

M.Lenti 2

News from MARCON

• Shipping at CERN of all the mirrors: end of 2010 – beginning of 2011

• 4 dummy segments ordered to be shaped and drilled as the mirrors (without any optical threatment) for our testing

26/11/2010

M.Lenti 3

Encoders

NANOS Instruments GmbHEncoders developed for PiezoMotorTwo pieces ordered

26/11/2010

M.Lenti 4

Leaf Springs• Full prototype realized• “leaf springs”: mirror hung through two holes• Mirror movement around x and y axis • pulled at 0 and 90 degrees • Mirror weight: counterbalance for vertical

movement• Leaf springs: counterbalance for horizontal

movement• Piezo-motor (final) used• 0.25 mm thick aluminium ribbon (direct

traction, no 90 deg deviation); l=250mm

dowel

piezo

piezo

piezo

dow

el

dowels

dowel

Leaf springs

26/11/2010

M.Lenti 5

Leaf Spring Prototype• For the horizontal plane (actuated by the leaf spring) the "zero" with the

ribbon mounted was with a 12 mrad angle deviation with respect to the "free" situation(no horiz ribbon fixed).

• I measured this both from the displacement at the ribbon fixation point and from the displacement of the laser spot on the photodiode.

• The force to be exerted to bring all the stuff in the horiz. "zero" position is 60 g (or 0.6 N) measured with a dynamometer; the force is roughly linear with the observed displacement of the laser spot on the photodiode.

• Use both an aluminum hexagon and a true glass mirror (pre-series mirror are with two holes in the back, lacking the central one)

• Reduce step size by a factor 5 w.r.t. last meeting

26/11/2010

M.Lenti 6

Leaf Spring PrototypeAluminum hexagon Glass mirror

65 μ

m

Glass MirrorDist. Mirror-phtdiode: 770 mm

Aluminum hexagondist. Mirror-phtdiode: 700 mm

From one point to the next: 20 microstep movements of the Piezo (6.25 μm)

26/11/2010

Spot position on the Photodiode

65 μ

m

50 μ

rad

50 μrad 50 μrad

50 μ

rad

M.Lenti 7

Single Dowel Prototype

• Put the actuating ribbons “parallel”• “twist” the actuating ribbons (90 degree from

the segment to the piezo)• Use a third ribbon for θZ stabilization• Reduce step size by a factor 5

26/11/2010

M.Lenti 8

Single dowel• Full prototype realized• “single dowel”: mirror hung at the center• Mirror movement around u and v axis

(instead of x and y)• pulled at ±45 degrees (axis decoupling)• Mirror weight: counterbalance for both

movements• Piezo-motor (final) used• 0.25 mm thick aluminium ribbon (direct

traction, no 90 deg deviation), 13 mm widedowel

piezo piezo

piezo

dowel

dowelstabilizer

26/11/2010

M.Lenti 9

Single Dowel

Twisted ribbon Twisted ribbonRibbons are parallel

θZ stabilizer θZ stabilizer

fixedfreefixed

θZ stabilizer

The stabilizer ribbon is fixedon the bottom corner of the Hexagon and at 500 mm on theright (available also on the leftbut not used)

26/11/2010

Actuating ribbons joints on theHexagon made horizontal using a level

10

Single dowel prototype

17.11.201016.11.2010

65 μ

m

From one point to the next: 20 microstep movements of the Piezo (6.25 μm)Piezo ribbon joint on the hexagon: 300 mm from the dowel

65 μ

m

26/11/2010 M.Lenti

Aluminum hexagon

Spot position on the Photodiode Aluminum hexagon: dist. Mirror-phtdiode: 700 mm40 μm on the photodiode 0.5*40 μm/700 mm = 28 μrad

6.25 μm/300 mm = 21μrad

50 μrad

50 μ

rad

50 μrad

50 μr

ad

M.Lenti 11

Conclusions

• Both approaches (leaf springs and single dowel) tested

• Two encoders ordered• 4 Dummy glass mirrors ordered

26/11/2010